1. Field of the invention
The present invention relates to a head access mechanism of the magnetic disk memory device for memorizing information by means of a rigid or flexible magnetic disk, more particularly, to a linear drive head access mechanism.
2. Description of the Prior Art
Generally, a magnetic disk device for memorizing information by means of a rigid or flexible magnetic disk is equipped with a head access mechanism for moving an electromagnetic head to a desired position on the disk surface when memorizing or reading an information.
A known type of head access mechanism includes a yoke in the shape of the letter E whose pair of magnetic gaps open on either side of the extension of the magnetic disk plane, a movable coil wound around a central portion of the yoke by passing through the magnetic gaps in turn, and an electromagnetic head which is attached to the movable coil via a carriage. Therefore, the magnetic head is allowed to gain access to a desired spot on the magnetic disk by displacing the movable coil along the central yoke.
In this type of prior art head access mechanism, the plane of placement of the magnetic disk and the loops of the magnetic circuits formed by the yokes are mutually orthogonal so that the maximum magnetic flux leak occurs in the extension of the plane which is perpendicular to the magnetic flux direction within the magnetic gaps. Since the straight line joining the magnetic head and the magnetic disk intersects the plane mentioned above, the magnetic head will find itself in an extremely strong magnetic flux leak in case the separation between the magnetic head and the yokes is not large enough. Therefore, in order to avoid a deterioration in the electromagnetic characteristics of the head it becomes necessary to maintain a sufficient separation between the magnetic head and the yokes, which in turn causes an increase in size and weight of the carriage, resulting in a degeneration of the energy efficiency due to an increased energy consumption required for driving the carriage.
Moreover, a large space is required along the vertical direction due to the structure of the yokes whose magnetic gaps open, opposing to each other, at the outer periphery of the magnetic disk in the upper and lower sides of the extension of the magnetic disk plane. In particular, when a rigid or flexible magnetic disk is used for situations where a high density recording is feasible, there exist cases wherein the use of stacked magnetic disks along the gravity direction is unnecessary. That is, in such a case there has persisted a problem that the large size of the head access mechanism takes up an excessive space along the gravity direction.